High shear blind fastener



I V 3 M "M 7m M 9 5m w 1m W H E m M a K. I. STUBBS HIGH SHEAR BLIND FASTENER Filed Feb. 24, 1947 Sept. 9, 1952 Patented Sept. 9, 1952 v UNITED STAT ES PATENT OFFICE HIGH SHEAR BLIND FASTENER Kenneth I. Stubbs, Los Angeles, Calif. Application February 24, 1947, Serial No. 730,450

4 Claims.

This invention relates to fastening devices and,

of an airplane to the structural framework, be-

cause of the fact that the' innerend ofthe fas-l tening element extends intoa spacethat is inaccessible, thus making it difiicult or impossible to position a nut'in such a manner that a screw can beengaged therewith, aswell as to hold the nut from turning while the screw isjbeing tightened. This difliculty in aircraft construction has been partially solved in the past'by permanently afiixing a nut to the innersuriace of'the inner,- most of the members to be fastened together in position to receive a screw after the parts have been assembled. This has often proved disadvantageous because of the impossibility of replacing the nut should it become damaged. An other partial solution was the use of explosive rivets, the inner end of which are swaged to riveted forinby -the explosion of a charge provided within the inner end of the rivet when sufficient heat iszapplied to the rivets outer end. This method also has frequently proved disad-r vantageous because of the impossibility of re-' moving the fastening'device without damage to the members joinedbythe rivet. j

It is an'object of the present invention to provide a fastening, device capable of solvingthis problem effectively by providing means operable from the accessibleside of a structure for positioning a nut within an inaccessible space within that structure and with its bore in register with a hole through one or more pieces of materiaFdefining' the inaccessible space, so that a screw thrust through thehole can enter the nutwithout any'necessityi for the operator to reach into'the space in ordertoobtain the proper positioning of the'nut or to hold the nut against turning whilej'the screw is being tightened A more detailed object of the present lnvention is to provide'fa fastening devicefof the general character described wherein the nutis carried by a stud which is adapted to extend through thehole in the members being fastened together,- and which is of such design ,that it is oapable of being manipulated from the outer, or ac: cessibleyside of the members, and which stud, moreover. is of tubular form whichpermitsthe screw to extend through the studinto proper a era n sm m it he n A further object in this connection is to provide a blind bolt construction as'described, wherein the hole through thefmembers being fastened together is substantially completely filled by the metal of which the fastening device is formed, thus yielding a joint ofmaximum ef-j:

ficiency in shear as well as in tension.

A still further object in this connection is -to form the nut of myimproved fastening device so that it is relatively long in propo-rtionto its width, its width being less than the outside dimention of the shanloof thestud softhat when the nut is turned in such a manner as to dispose, its longitudinal axis parallel to the axis of the stud, both the nut and the stud can be thrust readily through the hole in the members being fastened together, which hole need not be of greater diameter than the shank of the stud,

Another object is to fashion the nut in such a manner that its length is greater than the outside diameter of the stud and, hence, capable of engaging the innersurfaceof the innermost of the members beingfastened together, when the nut has been rotated through 90 after having been inserted lengthwise through the hole in the members, with the result that when the screw is thrust through the bore of the stud, engaged with the threads of the nut; and then tightened, themembers will be firmly clamped together between the head of the screw and the nut bearing against the inner surface of the innermost member. h h

"It is a further object of the present inven ti-on to provide a fastening device of the general character indicated wherein the nut is mounted upon one or more extensions on the inner'end of the stud, the nature of the mounting being such as to permit both the rotary motion of'the nut necessary to enable the nut to turn throu h at least the 90 of rotation hereinabove, referred to, and also the sliding movementtoward' the stud which is necessary topermit the nut to be drawn toward, and into clamping engagement .with the inner surface ofthe innermost of the members being ,fastened. I

Yet another object is so to designthe. means for mounting the nut upon the inner "end or the stud that rotary rnotion of;- the nut with respect to the stud and about the studs, axis is prevented, thus providing means accessible outside the structure for positivelyholding the nut against turning with the screw when the latter is tightened. 7 W

Another object is toprovide a'fastening' device of the blind,boltrtypeasfdescribed, which i's relatively simple in design 'and construction-and employed advantageously.

which is correspondingly inexpensive to manufacture, which lends itself readily to quantity production, which is possessed of several features of advantage which contribute to the ease and surety of its operation, and which is capable of clamping members together with fully as much pressure and as much surety against inadvertent dislodgment as any ordinary fastening device of more conventional design.

The invention possesses other objects and valuable features, some of which, with those enumerated, will be set forth in the following description of the preferred form of my invention illustrated in the drawing accompanying and forming part of the specification. It is to be understood that I do not limit myself .to the I showing made by the said drawing and description, as I may adopt variations of the preferred form within the scope of my invention as set forth in the claims.

Referring to the drawing:

Figure. '1 is a view in front elevation of a lap joint, the overlapping members of which are fastened together by means of fastening devices incorporatin the principles of the present invention.

Figure 2 is an enlarged longitudinal, medial, vertical, sectional view taken through one of the fastening devices of Figure 1 on the line 2-.-2 .of that figure with the direction of view as indicated. This figure shows the stud and nut in position to receive the tightened screw, but prior to engagement .of the latter with the nut.

Figure 3 is a view in side elevation of the fastening device of Figure 2, but showing its parts in the respective positions assumed thereby when the screw is tightened to its final clamping position.

Figure 4 is a longitudinal, medial, sectional view taken upon the line 4 l of Figure 3, with the direction of .view'as indicated.

' The drawing illustrates the preferred embodiment of my improved blind bolt as the medium with which the overlapping edges of two plates H and I2 are secured together with the understanding, however, that thereis no implication that this is the only type ofmemher for the interconnection of which the fastening devices of the present invention may be As illustrated, the fastening device comprises three principal memhere, to wit: a stud I 3, a screw it and a. hot it,

each ofv which parts, as well as their mannerof inter association, will be described in detail herein below.

The stud member {3 is a tubular form, being provided with an axial bore Ii extending corn.- pletely through its shank I 8, and a head It larger than and formed on the outer end of' the shank IS. The head I9 is alsopreferably provided with a counterbore .ZI' in its outer surface. A pair of fingers 22 rigid and preferably integral with the stud I3, extend beyond the inner end 23 of the studs shank I3, these fingers being disposedin spaced parallel relation and with their outer lateral faces 24 spaced from each other a distance no greater than thefoutside diameter of the shank I8, withjthe result that the fingers -22 do not interfere with thrustingthe shank {8 of the stud I3 through aligned'holes 2E and 2-? in the overlapping plates II and I2, to which holes the shank I8 is fitted. Each of the fingers 22 is provided with a longitudinally-extending slot 3!, each of which extends from a point 32, adjacent the outer end of the associated fingers 22 to a point 33 just beyond the inner end 23 of the studs shank 18, i. e., the distance from the point 33 to the head IQ of the stud I3, is slightly less than the distance between the studs inner end 23 and its head I9.

The screw I4 comprises a shank 36 and a head 37 on the outer end thereof, the diameter of the shank 36 being so'proportioned with respect to the internal diameter of the bore H of the stud l3 that it fits nicely therein. The inner end of the shank 36 is provided with threads 33 which extend along the shank toward the head 37 to a point 39 only slightly beyond the inner end 23 of the ,studs shank I8 when the screw I4 is in its final, tightened position.

Accordingly, the smoother unthreaded portion II of the shank 36 substantially completely fills the here I! of the stud I3. This detail is of importance when considered in connection with the fact that the shank [8 of the stud I 3 substantially completely fills the holes 25 and 2'! in the plates II and I2, respectively, because it develops the maximum cross-section of metal capable of resisting any tendency toward shearing of the fastening device, thus overcoming ,one of the principal objections of. toggle bolts of more conventional design which require an opening through the members to be interconnected which is larger than that portion ,of, the fastening device which occupies the hole when the fastenin device is'tightened.

Also, the head .37 of the screw [4 is preferably proportionedto fit nicely within the counterbore 2| of the studs head I9, With the result that when the fastening device is in its final, tightened relation, the'outer surface of the studs head, 19 and the outer surface of thescrewshead 3'I"ar.e substantially flush and present a substantially smooth outer end of the fastening device interrupted only by the kerf 42 in the head 3'! .of the screw 14.

Beyond the inner end of the threads .38, the shank .36 of the screw i4 is provided with an extension 43 of reduced diameter, this diameter .being no greater than'the root diameter of the threads 43. The inner end .of the extension 38.; instead of extending in a plane perpendicular to the axis of the screw, is disposedjobliquely there to, thus presenting an acute angle at the extreme innerend'of the extension 43 which, instead of being sharp, is formed about a short radiussoas to provide a rounded entering point 44.

The nut I6 is relatively ,long and narrow; vIts width, i. e., its dimension measured perpendicularly to the axis of its boreand. perpendicular to its two side faces 5| (see Figure 4,), is sufficiently less than .the distance between the two inner faces of the fingers 22 to permit the nut I6 to move freely therebetweell. vThe length of the nut,

i. e., its dimension measured perpendicularly to. and perpendicular to the two the axis of its bore end faces 52 (see Figure 2);, is materially greater than the diameter of "the shank 18 of, the stud I3.

Axiall-y aligned trunnion 53 extend outward from the tw o lateral faces '5I, theaxis of these trunnions 53 preferably being closely adjacent the workin face 54 of the nut, i. e., the face of the nut which bears against the inner face 56 of the innermost of the two plates I; when the fasten- I ing device is tightened.

By offsetting the trunnions 53 from the center of the nut to a position closely adjacent the nuts working'face 54, a structure is presented whereby the center of gravity of the nut is not intersected by the axis of its supporting trunnions, with the result that when the stud I3 is thrust through a hole, 'the'axisof which is horizontal or substanbeing understood that the/trunnions 53 are,

engagedwithin the two oppositeslots M of the arms 22, thereby mounting the nut 16 upon the arms 22 in such a manner that it. is capable of:

rotary motion with respect to the stud about the axis of its trunnions 53 and also capable of sliding movement toward and away from the inner end 23 of stud l3. However, possibly a more important advantage arising from the described, location of the trunnions 53 with their axis offset from thecenter-of the nut. toward the working face 54, is that when the nut 54 is swung to its Figure 2 position, i. ie., with its longitudinal-axis extending substantially parallel to the axis of stud l 3, the body of the nut 54 will be offset from the borel'l of the stud l3, far enoughfor the entering point 44 of the screw H to be thrustpastthat: end Bl ofthe nut which is directed toward the approaching end of the screw [4. Consequently, as the screw 14 is; advanced through the borell of the stud "[3, the inclined face defining the leading end: of the screw will become so engaged with the corner 62 of the nut 16 at theintersection of the working face 54 and the said end 6! that rotary; motion willybe imparted to the nut l6 about the axis of the trunnions 53, rotating it from that position which is illustrated in full lines in Figure 2, past the position which is illustrated in broken lines in the samefiigure; and into the position (not illustrated) wherein its bore is aligned with the bore Hand, hence, ready to receive the advancing screw l6. 1

However, when in this positionthe nut i6 is spaced away from the plate, l2 but it can be drawn toward theplate and into clamping engagement therewith by rotation of the screw [4 after it has been pushed through the bore ll far enough for its threads 38 to become engaged with the threads of nut l6. Thereafter, by rotating the screw l4, the engagement between its threads 38 and those of the nut will cause the nut to be drawn into clamping engagement with the plate l2. Inasmuch as the head 31 of the screw 14 bears against the outwardly-directed face of the stud l3 and the under face of the studs head l9 bears against the outer face of the outermost of the two plates H, tightening the screw 14 will impose tension thereupon, and thus exert a clamping action, pressing the two plates II and I2 firmly together.

Preferably, the trunnions 53, instead of being of circular cross-section, are substantially square bore ll with a relatively long and thin tool in such a'manner as to engage the nut 15 at a point offset. from the axis of the trunnions 53, and then by pushing with the tool to turn the nut.

This permits removal of the entire fastening devicefforsuchpurposes as separation of the plates I I and "or replacement of the nut I6 in they event it should become damaged, and constitutes one of the important advantagesof the blindbolt" of the present invention, inasmuch asthosexof more common design are not removable without damage to the members clamped thereby.-

Thus it may be seen'that I have provided a fastening device capable of positioning a, nut in registrywith alignedapertures in members to be clamped together and in position against the inner face of the innermost of those members to receive ascrew inserted through the same apertures, even though the space defined by those members is inaccessible. Moreover, the fastens, ing device of thepresent invention is capable of holding the nut stationary while the screw associated therewithis being tightened, this being accomplished by placing a wrench or other suitable holding tool upon the non-circular head l9 of, the stud 13 while the screw 14 is tightened by means of a screwdriver the blade of which is seatedini the kerf 42. Since the" nut '15 is narrower than thespace between the parallel fingers;,2;2 extending from the inner end lof the studs shank i8, thenut, can easily be placed in operative position simplyby thrusting it through the aligned holes in the members to be clamped and yet afterthe ,stud 13 of the screw 14 has been placed in position, these holes are substantially completely filled by the metal of'which the stud and screw are made, withthe result that the joint developed by means of the fastening devices of the present invention, develops the highest efficiencyinshear. i i

Iclaim: 1. Ina fastening devi'ceiof the'character described, a stud having an axial bore therethrough and so dimensioned that their greatest diagonal is equal to or slightly greater than the width of the associated slot 3|. Such arrangement causes the nut I6 to be releasably retained in that position in which it is illustrated in Figure 2, i. e., extending longitudinally parallel to the shank l8 of the stud l3, thus facilitating thrusting the nut l6 and the shank l8 of the stud through the aligned holes 26 and '21. However, the leverage exerted by the advancing inclined inner end of the screw [4 is suflicient to force the square trunnions to turn so as to swing the nut into position for the reception of screw l4 into the nuts bore. Obviously the non-circular trunnions 53 also facilitate holding the nut 52 in its Figure 2 position while the stud i3 is being withdrawn from the plates II and [2. In order to rotate the nut from its operative, position to the Figure 2 position and thus permit withdrawal of the stud, it is necessary only to reach through the studs and comprising a shank and means adjacent the outer end thereof providing an outer workgripping surface, a screw comprising a threaded shank receivable within said bore and a head on the outer end or said screw's shank, said screw's shank substantially filling said studs bore whereby said stud and screw co-operate in presenting a substantially solid section developing maximum resistance to shear, a nut providing an inner work-gripping surface, said nut being threaded complementarily to said screws shank, and

means mounting said nut on the inner end of said 7 stud for rotary movement about an axis perpen dicular to the bore of said nut and for sliding movement axially of said stud, said nut-mounting means holding said nut against turning with respect to said stud about said studs axis, and said nut being extended in a direction perpendicular to its bore to a length greater than the diameter of said stud.

2. In a fastening device of the character described, a stud having an axial bore therethrough and comprising a shank and means adjacent the outer end thereof providing an outer workgripping surface, a screw comprising a threaded shank receivable within said bore and a head on the outer end of said screw's shank, said screw's shank substantially filling said studs bore whereby said stud and screw co-operate in presenting a substantially solid section developing maximum resistance to shear, a nut providing an inner ea -res Work-gripping surface, said nut being threaded,

complementarily' to isaidzscrews shank," {and means'flmounting 'sai-dsnut on'the inner end of said stud for rotary movement :about an axis mounting means holding said nut against turning with respect to said stud about said studs axis, and said nut :being extended. in a direction 'per pendicular to its bore toalength greater than the diameter of said stud; and the width of-said nut measured parallel to the axis of its rotational mounting being at least as small as the diameter of said stud 'wherebysaid nut is enabled to pass through any hole adapted to receive said stud when said nut is turned to that position in which its length extends parallel to said stud.

.13; In a fastening device of the character described, aa stud'havingan axial bore therethrough, and ;.comprising a shank and ahead on the outer end of said shank, a screw comprising a threaded shank receivable within said 'studs bore and a head on the outer end of said screws shank, said screws shank substantially corresponding in diameter to said studs bore whereby said stud and screw co-operate in presenting a substantially solid sectionxdeveloping maximum shear strength, a pair of spaced fing'ers'rigid with said studs shank and extending beyond the inner end thereof, each of said fingers having a slot extend ing longitudinally thereof, a nut disposed between saidfingers, and axially aligned trunnions extending laterally from said nut and intosaid slots toimountsaid nut on said 'fin'gers thereupon for sliding movement longitudinally thereof and for rotary movement with respect thereto about an axisextending laterally of said nut and p-erpene diculartosaid nuts bore, said nutlbeing extended in a direction perpendicular to its bore and perpendicular to its said lateral axis to a length greater than the diameter of said studs shank.

4. 'In aafastem'ng device of the character de- 8 scribed, a studliaving ran Iaxiatlbore therethiaough; andcomprising"ashank and a headi'on the outer end of said shank, ,a screw comprising afthreadgd shank receivable within said stud sboreand a head on the :outer end of said screwfs, shank, 1a.-

p'a'ir of longitudinally slotted fingersrigid with said studs shank and extending beyond the ine ner (end thereof iinxspa'ced parallel re1ation,;a nut :disposed between said fingers and aipair oi axially aligned 'trunnions extending laterally from said nut and into rotatable and slidable en gagernent within -the slots insaid .fingers,sat least one of said tirunn'ions being of non-circular 'crosssectional form, the longest diameter ofsaidnon circular trunnion being slightly greater thflflith'e width of the associated one :of :said slots i'to 'retain said nut in selected position about' the axis. o'f'said trun nion's but said largest diam'eterlbeirg,

Number Name Date a 991,426 Clements May '2, 1 911 1,352,919 Salmons Sept. 14, I920 $404,169 Gidden July-'16, 1946 {FOREIGN PATENTS I r a Number Country Date H amusemen s 7 

